This disclosure relates to a gas turbine engine, and more particularly to a variable area turbine arrangement.
Gas turbine engines typically include at least a compressor section, a combustor section and a turbine section. In general, during operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases flow through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads.
The compressor and turbine sections of a gas turbine engine typically include alternating rows of rotating blades and flow directing vanes. In the turbine section, the rotating blades extract energy from the airflow that is communicated through the gas turbine engine, while the vanes direct the airflow to a downstream row of blades.
The vanes can be manufactured to a fixed flow area that is optimized for a single flight point. Alternatively, it is possible to alter the flow area between two adjacent vanes by providing one or more variable vanes that rotate about a given axis to vary the flow area. Altering the flow area in this manner can expose downstream components to incidence angle variation. In other words, the flow angle of the hot combustion gases may change as it is communicated to downstream locations by rotating the variable vanes at an upstream location.